Re: Why did Jericho left in 2005?
Jericho was burnt out after spending 15 years wrestling non-stop, and he saw the direction his career was heading, so he decided to step away in order to focus on other pursuits such as Fozzy and acting.
By 2005 he had gone from the occasional main-eventer to the constant midcarder, and I believe he thought that if he didn't make a change quickly, he'd be painted with that brush for the rest of his career. Turns out stepping away was probably one of the smartest decisions Jericho ever made. It reinvigorated his status/passion and helped facilitate that amazing heel run from 2008 onwards.